The SD Association has announced the SD 8.0 Specification for SD Express memory cards, which have the same size and form factor as the SD cards on the market for many years. Where SD Express cards improve significantly is on data transfer speed thanks to the new specification leveraging PCIe 4.0 to deliver maximum transfer speeds of nearly 4 GB/s.

The new cards continue to use the NVMe Express upper-layer protocol to enable advanced memory access mechanisms. While SD Express memory cards have faster data transfer than current cards, they maintain backward compatibility. Data transfer speeds offered by SD Express bring new storage opportunities for devices with demanding performance levels across multiple industries.

SD Express will be offered on SDHC, SDXC, and SDUC memory cards. The SD 8.0 specification will support two transfer speed options for SD Express memory cards. Transfer speeds supported by PCIe 3.0 x2 or PCIe 4.0 x1 architectures is up to approximately 2 GB/s, with the PCIe 4.0 x2 specification required to reach 4 GB/s. Physically, SD Express cards supporting PCIe 4.0 x1 will have the same form factor defined for SD 7.0 cards with a second row of pins to deliver transfer speeds of up to 2 GB/s.

Cards supporting dual PCIe lanes, such as 3.0 x2 or 4.0 x2, will have three rows of pins. Companies producing the cards will be able to use existing test equipment saving production and development costs. Data transfer speeds of up to 4 GB/s combined with the high capacity available on memory cards will make it faster for end-users to move large files created by some devices to their computer. SD Express transfer speeds are nearing the data transfer speeds available for some SSDs. We recently talked about a PCIe 4.0 SSD from KINGMAX that was capable of 5 GB/s reads.